Background: The management of moderate and severe slipped capital femoral epiphysis is still an issue. The main concern is represented by the choice of an intra-articular or an extra-articular osteotomy to correct the deformity. Theoretically, the intra-articular osteotomy allows the best correction, but it is technically demanding and involves a higher risk of avascular necrosis (AVN); conversely, an extra-articular intertrochanteric osteotomy (ITO) is easier and involves a lower risk of early complications, but may lead to femoroacetabular impingement, resulting in early osteoarthritis and the need for total hip replacement (THR).The aim of this study was to analyze the long-term survivorship free from THR after combined epiphysiodesis and Imhauser ITO.
Methods: From 1975 to 2000, 45 patients (53 hips) underwent a combined epiphysiodesis and Imhauser ITO. There were 27 male and 18 female patients with an average age of 12.8±1.9 years. All cases showed a posterior sloping angle >40 degrees (mean, 69±16 degrees). The cumulative survivorship was determined according to Kaplan and Meier, with the end point defined as conversion to THR.
Results: A total of 6 patients (6 hips; 11%) had a follow-up <2 years. Among them, no postoperative complications occurred. For the remaining 39 patients (47 hips, 89%), the mean follow-up was 21±11 years. Four early postoperative complications were reported (2 AVN, 2 chondrolysis). The cumulative 39 years' survivorship free from THR was 68.5% (95% confidence interval, 42.4%-84.7%). The age at surgery (hazard ratio=1.849 per year older, P=0.017) and the postoperative onset of AVN or chondrolysis (hazard ratio=10.146, P=0.010) affected the long-term prognosis significantly.
Conclusions: The combined epiphysiodesis and Imhauser ITO is a valid surgical option in moderate to severe slipped capital femoral epiphysis, preserving the natural hip for at least 39 years in the majority of the patients. Care must be taken to avoid AVN or chondrolysis. The age at surgery affects the prognosis negatively.
Level of evidence: Level III-a retrospective study.